This might seem a strange notion since we all know that the TV does not get Oric sound but instead its channeled to the internal speaker.
However there is a distortion of sound on the tv speaker when things change on the screen.
Those mad C64 sceners have even produced crude samples by changing the screen colours to manipulate the sound interference.

This technique goes as far back as the ZX81. If you know the ZX81, you'll be aware it has no sound output at all.

The ZX81 had two modes, fast and slow (or slow and slower still as the old gag says). In slow mode, the system works much like any other computer, but in fast mode it disables the screen display while it works, only turning it back on once its finished. By varying the on/off duration at rapid speeds, its possible to get white noise tones from the disabled screen as the tv effectively has no signal.

Not sure it'd work with a modern TFT display, but it (sort of) works with an old CRT.